21204424220 has 24 divisors (see below), whose sum is σ = 50890618464. Its totient is φ = 7270088256.

The previous prime is 21204424217. The next prime is 21204424229. The reversal of 21204424220 is 2242440212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204424229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75729947 + ... + 75730226.

It is an arithmetic number, because the mean of its divisors is an integer number (2120442436).

Almost surely, 2^21204424220 is an apocalyptic number.

21204424220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204424220 is an abundant number, since it is smaller than the sum of its proper divisors (29686194244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21204424220 is a wasteful number, since it uses less digits than its factorization.

21204424220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151460189 (or 151460187 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 23.

Adding to 21204424220 its reverse (2242440212), we get a palindrome (23446864432).

The spelling of 21204424220 in words is "twenty-one billion, two hundred four million, four hundred twenty-four thousand, two hundred twenty".